Objective:

To find the square or square roots of numbers.

General:

• The A and B scales are identical, dual-decade scales.
• The first decade runs from 1 to 10 and the second from 10 to 100.
• The A scale is generally located on the body and the B scale is located on the slider.  Not all slide rules have these scales.
• The A scale is used in conjunction with the D scale and the B scale is used in conjunction with the C scale.
• Mathematically, the principle of having two logarithmic decades is the fact

Method for finding Squares:

either ...

• Move the cursor to the value on the D scale to find the square of.
• Read the result on the A scale.

or ...

• Move the cursor to the value on the C scale to find the square of.
• Read the result on the B scale.

Method for finding Square Roots:

either ...

• Move the cursor to the value on the A scale to find the square root of.
• Read the result on the D scale.

or ...

• Move the cursor to the value on the B scale to find the square root of.
• Read the result on the C scale.

Example 1:  Find the value of 1.12²

• Move the cursor to D1.12
• Read the result A1.25

Example 2: Find the value of 8.65²

• Move the cursor to D8.65
• Read the result A74.8

Example 3: Find the square root of 7.6

• Move the cursor to A7.6
• Read the result D2.76

Example 4: Find the square root of 84

• Move the cursor to A84
• Read the result D9.17

Practice Questions:  Calculate the following.

1. 8.5² (Ans: 72.3)
2. 1.36² (Ans: 1.85)
3. √50 (Ans: 7.08)
4. √2.65 (Ans: 1.63)
5. √74 (Ans: 8.6)